MIDTERM 07 - Mycobacteria and Atypical Pneumonia Flashcards
Are rod-shaped, obligate aerobic bacteria; is an acid-fast bacteria that cannot be classified as gram-positive or gram-negative
Mycobacteria
Bacteria that resist decolorization by acid or alcohol
Acid fast bacteria
Cultured using inspissated egg media (ex. Lowenstein-Jensen); causes primary complex, latent TB, and reactivation/secondary TB (Mycobacterium species)
Mycobacterium tuberculosis/Koch’s bacillus
Media that contains salts, glycerol, and complex organic substances; used to culture Mycobacterium tuberculosis
Inspissated egg media (Ex. Lowenstein-Jensen)
Responsible for acid fastness (Mycobacterium tuberculosis virulence factors)
Lipids
Can cause granuloma formation; resists drying (Mycobacterium tuberculosis virulence factors)
Mycolic acid
Inhibits migration of leukocytes; causes chronic granulomas (Mycobacterium tuberculosis virulence factors)
Cord factor
Induces caseous necrosis (Mycobacterium tuberculosis virulence factors)
Phosphatides
Elicit tuberculin reaction and antibody production (Mycobacterium tuberculosis virulence factors)
Proteins
Characterized by granuloma (tubercle) formation due to migration of macrophages (Clinical findings of Mycobacterium tuberculosis)
Primary complex
Characterized by dormancy of bacilli in the granuloma (Clinical findings of Mycobacterium tuberculosis)
Latent TB
Characterized by reactivation of dormant bacilli due to depressed cell-mediated immunity or reinfection (Clinical findings of Mycobacterium tuberculosis)
Reactivation/Secondary TB
Refers to the spread of Mycobacterium tuberculosis through regional lymph nodes
Lymphatic spread
Refers to the spread of Mycobacterium tuberculosis to all organs (Miliary distribution)
Hematogenous spread
Occurs usually in childhood; usually involves the base of the lungs (Clinical findings of Mycobacterium tuberculosis)
Primary complex
Has no clinical manifestations; host is noninfectious (Clinical findings of Mycobacterium tuberculosis)
Latent TB
May be due to tubercle bacilli that have survived the primary lesion; usually involves the apex of the lung, where O2 tension is the highest (Clinical findings of Mycobacterium tuberculosis)
Reactivation/Secondary TB
Due to dormant bacilli in the primary lesion; more common (Causes of Reactivation/Secondary TB)
Endogenous
Due to reinfection (Causes of Reactivation/Secondary TB)
Exogenous
Characterized by fatigue, weakness, weight loss, fever, and night sweats (Clinical findings of Mycobacterium tuberculosis)
Tuberculosis (Koch’s disease)
Characterized by chronic cough and hemoptysis (Types of tuberculosis)
Pulmonary TB
Involves ≥2 adjacent vertebral bodies (Types of tuberculosis)
Spinal TB (Pott’s disease)
Characterized by bloodstream dissemination and infection of many organs (Types of tuberculosis)
Miliary TB
Used to test for tuberculosis; patient is examined within 48-72 hours after injection; a positive result is an induration/wheal formation
Tuberculin skin test (TST)/Mantoux test
Derivative that is obtained by chemical fractionation of old tuberculin (A concentrated filtrate of broth in which tubercle bacilli have grown for 6 weeks); injected on the inner surface of the forearm
Purified protein derivative (PPD)
Diagnosis for tuberculosis with a low sensitivity (40-60%); 2 sputum specimens are collected early in the morning
Acid fast smear/AFB microscopy/Ziehl-Neelsen method
Diagnosis for tuberculosis that has a high sensitivity but poor specificity; for diagnosis of PTB in children who cannot expectorate (<5 y/o)
Chest X-ray
Used for rapid diagnosis of TB with high specificity and sensitivity
Gene Xpert MTB/RIF
An intradermal, attenuated vaccine derived from Mycobacterium bovis that is given at birth and is used for Mycobacterium tuberculosis prevention
Bacillus Calmette-Guérin (BCG) vaccine
Meaning of DOTS (Mycobacterium tuberculosis treatment)
Directly Observed Treatment, Short Course
4 drugs that are 1st line agents used for treatment of Mycobacterium tuberculosis (RIPE/HRZE)
Rifampicin, Isoniazid, Pyrazinamide, Ethambutol
Tuberculosis that is resistant to one 1st line agent (Types of resistant tuberculosis)
Monoresistant TB
Tuberculosis that is resistant to rifampicin (Types of resistant tuberculosis)
Rifampicin resistant (RR) tuberculosis